title: Quantitative coronary angiography: impact of imaging parameters on accuracy and confidence interval.
abstract: The impact of patient size, image intensifier (II) dose, focal spot size, and matrix size on accuracy and the confidence interval of a quantitative coronary analysis (QCA) system has been investigated using calibrated tube phantoms in combination with a varying amount of water representing the patient's size. We found good accuracy for the whole range of patients' sizes (15-30 cm H2O) except that a 0.5-mm vessel diameter (phi) can no longer be measured at > or = 25 cm H2O. Moreover, at 1-mm vessel phi gives no reliable confidence interval for > or = 30 cm H2O. A small focus (F = 0.4 mm) is favorable for small objects (< or = 15 cm H2O) only. For larger patient sizes the lack of contrast due to higher kilovoltage compensates the improved resolution. Low digital "cine dose" (e.g., 0.1 microGy/f at 17 cm II) is acceptable except for 0.5 mm vessel phi. Better contrast compensates for the increased noise. There is a small improvement in accuracy and confidence interval for vessels < or = 1.0 mm phi using the matrix 1024(2). The HICOR system allows one to stay within the DICOM card standard (matrix 512(2) using the mode "acquisition zoom" while providing high resolution in a limited field size.
authors.affiliation: Siemens AG Medical Engineering, Forchheim, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Seissl
authors.forename: K
authors.initials: K
authors.lastname: Peukert
authors.forename: B
authors.initials: B
authors.lastname: Geiger
authors.forename: B J
authors.initials: BJ
authors.lastname: Verstraelen
mesh_terms: D002138:Calibration; D016001:Confidence Intervals; D017023:Coronary Angiography / Q000379:methods*; D006801:Humans; D019047:Phantoms, Imaging; D011857:Radiographic Image Interpretation, Computer-Assisted; D015203:Reproducibility of Results